16,20-diketo steroids and process for preparing same



U ited State Patent mzomncn'ro-srunoms PROCESSFIOR" PREPARING SAME IoseEtELHerZ and-Josef Fried, New Brunswick,.NJ., as.-=

signors to Olin Mathieson Chemical Corporation, New

15 Claims. c1. zen-497.1)

This invention relates to a new class of steroids and a process for preparing the same, and more particularly is concerned with new 16,20-diketo-steroids and their method of manufacture.

Prior to this invention, 16,20 diketo-steroids were unknown, since there was no. operative process for preparing them. Any attemptt'o oxidize a lfi-hydroxy-ZO-keto steroid-unden the: usual;oxidizing;conditionsiwitli-ordinary oxidizing agents either. cleaved. the D.-ring orxoxidized the I Z-side chain to. an acid group.- We have now found-that by, practicing, this, invention, a l6 hydroxy-20 keto steroid may be oxidized to the corresponding l 6',20 }diketo. steroid;

object, ofv this invention therefore, is, to. prodiice 1 W: steroid derivatives having, oxo groups (or groups. readily convertible thereto, such as acetalCradical's). in the; 1'6"- and 20 positions;

Another object of this invention is the provision. of; an, advantageous process. for oxidizing l'fif-liydroxy, steroids.

These objects are achieved by reacting a? l'b-liydroxy steroidwith an oxidizing agent containing a hexavalent. chromium (chromic): ion in the absence offexcess acid (by excess acid is meant acid other than that required to. bind. the resulting reducedchromicion as a salt).

7 Although the process of this invention is operative. to oxidize any IG-hydroxy-st'eroid' to the corresponding 16-keto steroid, and hence includes oxidizing those steroids of theandrostane (including the androst'ene' and etiocholane) series,,as well. as: those steroids of the pregnane (including the pregnene, pregnadiene', pregnatri'ene, etc., and allopregnane) series, the process is especially advantageous when applied; to-a pregnane-derivativehaving a 16 hydroxy and 20ketorsubstituent,since the oxidation conditions previously, known wouldtcleayensuch a pregnane derivative. o1;- cause-tlieoxidation, or 1QQfi the l7-carbon chaiiL. a

The new steroids prodilced by the practice of this invention are 16,20-diketo-pregnane derivatives having the skeleton structure;

These steroids are mineralocorticoids which cause the retention of sodium andcliloride ions in animals and man.

The: starting materials useful in this process are any lifi-hydroxy steroids; The preferred" compounds, how everg-are: L6=hydifoxy 20rketo pregnane derivatives, where? int the; Ifi-hydroxy radical. maybeiin either the alpha "ice or beta positions l6a-hydroxy steroids utilizable as starting. materialsv are exemplified bythose disclosed in; the. applications of- Perlman', et al., Serial. No. 239,018,; filed July. 27, 1951, now Patent No. 2,709,705, granted. May 3l', 1955, andFriedet al., Serial No. 453,411, filed: on: evendate herewith, and now abandoned] These pregnanederivatives, in addition to the 16-hydroxy and 20 -keto substituents, maycarry any other radicals (not altered bychromicacid) on the carbon nucleusor 17-. sideehainand may be. saturated: or partially saturated. lzlx amples. of suitable substituents are hydrocarborr groups; acid,-ester,. or amide radicals; ether, tertiary hydroxy or" acylated secondary or primary hydroxy radicals; nitrogen; containing radicals such as nitro or acylated amino groups; and. halogens.

,1 Examples of suitable starting materials are. the. 1.6 0:- liydroxyderivatives-of: progesterone; hydroxylated pro gesterone; halogenated progesterone; pregnenolone; pregnanolonm. desoxycorticosterone 2l-monoacylate; cortisone; 17-hydroxycorticosterone; dehydrocorticoster'-- one; 17a-hydroxy-ll-desoxycorticosterone; diketo-M-androstene; testosterone; corticosterone; aldosterone; etc. as well as their esters (when a second hydroxy group is? present such-as a lower fatty ester (i.e. acetic, propionic butyric, etc.) or an aromatic ester (i.e. benzoic, naph thoic, etc.) or a substituted derivative thereof.

These compounds are converted by the practice of-this invention to the corresponding l6-keto derivatives.- 15

a second unprotected hydroxy group is present, it too is? oxidized to a keto group, provided that it is the sole substituent on the hydroxylated-carbon atom.

A particularly preferred class of starting; compounds: isL-that having the following general formula:

wherein the 45 position is double-bonded or saturated (the 4,5-double-bonded steroids are preferred), and' wherein R is hydrogen; R is hydroxy, or together R and R is oxo (keto) or a. group convertible thereto by hydrolysis (e.g. ketal), R and R as OX0 being preferred; Z is hydrogen: ora-hydroxy; B is a keto: radical 0 1?3; proteeted, keto radical such as. a; ketal radical; and Y iSl hydrogen; halogen-,, hydroxy,,or R0, wherein R" is an;

organic radical such as an acyl radical, particularly acar-- bonylradical- (suchta s acetyl, propionyl; butyryl, benzoyL, napthoyL. etc). or an: organic radical connected to.- the oxygenfthrough. a. carbon to. oxygenbonisuchv as a. by:-

wherein the 4,5 position is double-bonded or saturated (preferably double-bonded); R, R, Z, and B are as above-defined; and R is hydrogen and R"" is Y or together R and R"' is keto.

The 16-keto derivatives of this invention are prepared by reacting the corresponding 16-hydroxy steroids with an oxidizing agent under suitable conditions. The oxidizing agent used is a compound containing a hexavalent chromium ion and includes a salt of chromic acid, chromic anyhdride (chromic trioxide), or a chromate ester. Of these, chromic anhydride is preferred.

I The reaction is carried out in the absence of excess acid [by excess acid is meant acid other than that required to bind the resulting reduced chromic (chromous) ion as a salt] and in an organic solvent which is unreactive towards the chromic group. Suitable solvents include ketones, such as acetone, methyl ethyl ketone, etc.; ethers, such as diethyl ether, dipropyl ether; cyclic others, such as dioxane and tetrahydrofuran; etc.

' In order to bind the reduced chromic ion as a salt, it is preferred that the oxidation reaction be carried out in the presence of a mineral acid present in stoichiometric amounts with the chromic oxidizing agent. Among the acids which may be used are hydrochloric acid, sulfuric acid, nitric acid, etc., sulfuric acid being preferred. Any substantial excess of acid beyond that necessary to bind the resulting chromous ion should be avoided, however, since such excess may cause undesired additional oxidations to occur.

The reaction is preferably conducted at a controlled temperature of less than 25 C. and more particularly at a temperature less than 15 C. under substantially anhydrous conditions. The reaction should be carried out under non-acid conditions, since the use of excess acid as either a solvent (i.e. acetic acid solvent) or as an oxidizing agent (i.e. excess sulfuric acid) will tend to oxidize the steroid beyond the desired l6-keto derivatives and cause cleavage of the D-ring or oxidation of the 17- side chain. The 16-keto steroid may be recovered from the reaction mixture in a number of ways, as, for example, by extraction with ether.

If the starting material has been esterified or etherified to prevent the oxidation of hydroxy groups other than the 16-hydroxy radical, the resulting 16-keto derivatives may be saponified (hydrolyzed), as by alkali metal alcoholates (i.e. sodium methylate), to convert the protected hydroxy group to its free hydroxy form.

The following examples are illustrative of the invention.

EXAMPLE 1 J 6-ket0 progesterone 350 mg. of 16a-hydroxyprogesterone are dissolved in 150 ml. acetone and the solution is cooled to 7 C. To this solution is added with stirring over a period of 15 minutes a solution of 150 mg. of CrO and 240 mg. of concentrated H 50 in 75 ml. of water. The reaction mixture is then filtered, diluted with 20 ml. water and the acetone removed in vacuo. The resulting aqueous suspension is extracted with ether, the other solution washedtwice with 10 ml. of saturated NaHCO solution and twice with 1 N NaOH. From the above ether solution about 165 mg. of starting material is recovered by evaporation of the solvent and crystallization from acetone. The combined NaOH extracts are acidified with cold hydrochloric acid and 16-ketoprogesterone is extracted into ether. The resulting ether extract is washed with NaHCO solution and water, dried over sodium sulfate and evaporated to dryness in vacuo. About 126 mg. of crude, crystalline 16-ketoprogesterone is obtained which after crystallization from acetone-ether (about 98 mg.) has the following properties: needles M.P. 162 165 G; [:1 +37 (c.=0.77 in chloroform), +27

(c.=0.30 in methanol), (c.=0.30 in .0185 N KOHMeOH);

x312 239 m (e==21,500), 236 m l (E=6000) (c.=

0.0045%); A531? KOH in MeOH 241 m (e=18,500),

308 my. (e=27,000); xgfif 5.74, 5.90, 6.02, 6.22,.

Analysis.Calcd. for C H O (328.44): C, 76.79; H, 8.59. Found: C, 76.76; H, 8.62.

The alcoholic solution of 16-ketoprogesterone gives an intense purple color with ferric chloride, indicative of its partially enolic nature.

The steroid has the following formula:

EXAMPLE 2 16-keto-1I-desoxycorticosterone 21 -benzoate (A -preg- Irene-21-0l-3,16,20-tri0ne 21 -benzoate) mg. of l6a-hydroxy-1l-desoxycorticosterone 21- benzoate is dissolved in 25 ml. of acetone and the solution cooled to 8 C. To this solution is added with stirring 0.14 ml. of a solution (200 mg. CIO;,, 320 mg. H 80 concentrated, made up to 1 ml.) containing 28 mg. CrO (1.2 equivalents). After five minutes ethanol is added and the precipitate of Cr (SO filtered 01f. The acetone is then evaporated in vacuo, the resulting residue dissolved in a mixture of ether and chloroform and extracted with ice-cold NaHCO followed by icecold 1 N' NaOH. The NaOH-solution is immediately neutralized with ice-cold HCl and extracted with ether. The dried ether solution upon evaporation yields about 56 mg. of crude crystalline 16-keto-11-desoxycorticosterone 21-benzoate, which after recrystallization from acetone has the following properties: M.P. 198-199.5 C.; [aJ -6 (c.=0.34 in chloroform);

x512 233. m 29,500), 273 m (5:2900), 281 my (e=2700; X322" 234 m (e=25,600), 306 m (e= Analysis.-Calcd. for C H O (448.54): C, 74.97; H, 7.19. Found: C, 74.84; H, 7.06.

A -pregnene-2l-ol-3,16,20-trione 2l-benzoate gives an intense coloration with ferric chloride.

The steroid has the following formula:

EXAMPLE 3 16-ket0-1I-desoxycorticosterane acetate (M-pregnene-ZI 0l-3,16,20-tri0ne acetate) tion of 200 mg. CrO 320 mg. of concentrated H SO made'up fof l m1; with water). After 10 minutes; the" r ('SO which precipitated is filtered off, the acetone evaporated vacuo; the residue dissolved in ether. washed with -ice-cold N3HO solution and then withice-cold l NNaOHf NaOI-I extract is acidi fied with cold HCl, extracted with ether and the ether solution evaporated todryness in vacuo. About 40 mg. of an oil is obtained,. which even after chromatography on silica cannot be crystallized. The amorphous 16- keto-ll-desoxycorticosterone acetate has [c15 -12 C. (c.=0.215 in chloroform) and gives an intense coloration with ferric chloride.

EXAMPLE 1 4 1 6-ket0-11 desoxycorticosterone (A -pregnene-21 -ol-3,1 6, ZO-m'one 21.5, mg. of the, chromatographed acetate of Exam-. ple 3 (representingja: ooimeliiaing the'chlo'roform up. to'f chloroforiii afc'etoi e (111') eluates) is. dissolved in 2 ml;-methanb1'aiidf0l5 m1} o'faimethanolic' solution of. sodium methylate' (containing. 6 ing. Na). is. added. The mixture is. allowedf t'o stiaiid'at room temperature. under N for 30mi'nut'es; A few drops of'glacial. acetic acidv and 5 ml. water are.added,---the.methanol removed in vacuo and the aqueous suspension extracted with chloro-- form. About L8 mg. of oily: 1.6-kfeto-1 .'1T-desoxycorticosterone ['od +79 (.fc.= ll9f in chloroform) are ob-. tainedi.

ACME

mix.

The st'erofid has" the rau'ewihg-rbrmulaaaaoa.

FGw-hydroziys'l-lz-desoxycorticostflonez is also usefuh "as ast'a'r ting'. material in. the preparation: of; A -androstene='3.; l6=dione, a: new steroid Which- .a; protein" anabolic agent. The processi-ofi this conversion is. more fully. disclosed by the following schematic analysis and ex'- amples:

EXAMPLE I lom-hydroxy-Azmdrostene-3-0ne=17 3 carb0xylic acid (11);

To a solution of 100 mg. of l6w-liyd'roxy-ll-de'soxycorticosterone (I)? in ml; of'pure: dioxane is, added 5 a solution of 132 mg:. of.periodic acid: dihydrate in: 10

ml; of waterr The-mixture is: allowed to remaimat room temperature for 3 hours andiafter adding 5 ml: of water: is placed in the refrigerator for an additional 1 2 hou'rs. crystalline. product separates out (about 86 mg.), 30 which" .could' not be recrystallized from the common organic solvent because of its extreme insolubility; M .Bl 315-317 C. (dec.);..

N32" 3.05 (OH); 5.76;; and 5.82 (COOH), 6.04;. and

6.09m (A -3-ketone) Analysis.-Calc'cl. 61: C H O (332.42): C, 72.26; H, 8.49. Found: 0;.7151; H} 7.97.

EXAMPLE 6 46 Methyl I6u-hydr0xy-A -androstene-3one-I7,8-carboxylate (III) To a suspension of M-androstene-1'6u-ol-3-one-17pcarboxylicacid. II). (.60 mg.) in methanol is added ex cess dia zfon letlianeether- The aciddissolves slowly; 5' with; evolution. of. nitrogen andafter hoursthe. re sulting solutiondst-eyaporatei to dryness-in.vacuo.- The; QSi PA me s s cr t ll ze readily ro ce o e e seue and-m l at; 6; 4 1) to? 0.32r'n el1 loroo131'p)r;:

8521239 1 31# 915 3;,AEiE E (Q );v 2 1 nd "538%; ('stercarb onyl); 6i05pand 6.22 (-A' 3 liej7oriei f Analysis.-Calcd.. for C H O (346.45): C, 72.80; H, 8.73. Found: C,' 73.08; H, 8.49.

EXAMPLE 7 Methyl A*-andf6st enel=3,1o dione-l 7 fi-carboxyla'te (IV) To a solution of methyl A -androstene-16oa-ol-3-onel7p-carboxylate (III) (35 mg.) in 1 ml. of glacial acetic acid is added dropwise a solution of 10 mg. of chromic acid in 0.2 ml. of acetic acid. After 15 minutes at room temperature the excess chromic acid is destroyed with ethanol and the mixture is concentrated to small volume. The. residue is distributed between chloroform. andwater, the chloroform: solution extracted with dilute. bicarbonate, and water. and the solvent removed in vacuo... crystalline: residueon. recrystallization from acetone}. hexane yields about 10 mg. of the pure ketoester of melting point l39-142 C. and [111 27 (c., 0.30

in chloroform);

)\'2%KOH in MeOH 241 m (e=20,000), 285 mu (e=l6,500); A232 5.78 and 5.82 (ester carbonyl), 5.98;. and 6.17 (A -3- ketone) An alcoholic solution of the ketoester gives a purple coloration with ferric chloride.

Analysis.-Calcd. for C H O (344.44): C, 73.22; H, 8.19. Found: C, 73.03; H, 8.05.

EXAMPLE 8 A -andrstene-3J 6-di0ne V) A solution of crude methyl A -androstene-3,16-dionel7fi-carboxylate (IV) (234 mg.) in ml. of purified dioxane and 10 ml. of 2 N aqueous hydrochloric acid is refluxed for six hours and the liberated CO swept with N into barium hydroxide solution. After cooling to room temperature chloroform (100 ml.) is added to the reaction mixture, the resulting chloroform-dioxane layer is separated ofi, washed with water and dilute sodium bicarbonate and evaporated to dryness. Crystallization of the residue (about 146 mg.) from methanol-ether yields about 70 mg. of pure A -androstene-3,l6-dione, M.P. ISO-152 C.; [111 -9 6 (c., 0.85 in chloroform);

M23. 240 u Mill? and 6.18 (A -3-ketone) Analysis.--Calcd. for C H O (286.40): C, 79.68;

H, 9.15. Found: C, 79.71; H, 8.91.

The invention may be otherwise embodied within the scope of the appended claims.

. We claim:

l. A process of oxidizing a 16-hydroxy steroid which comprises reacting a 16-hydroxy steroid of the general formula (IJHQY C=O CHiY wherein Z is selected from the group consisting of hydrogen and a-hYdIOXY; and Y is selected from the group consisting of hydrogen, halogen, hydroxy, lower alkanoyloxy and benzoxy, in an organic solvent in theabsence comprises reacting a 16-hydroxy steroid of the general formula ('JILY wherein Z is selected from the group consisting of hydrogen and a-hydroxy;'a.nd Y is selected from the group consisting of hydrogen, halogen, hydroxy, lower alkanoyloxy and benzoxy, in a non-acidic solvent with an oxidizing agent comprising a stoichiometric amount of a chromic oxidizing agent and a mineral acid, and recovering the product thus produced.

4. The process of claim 3 wherein the steroid is hydroxyprogesterone.

5. The process of claim 3 wherein the steroid is an ester of 16a-hydroxy-desoxycorticosterone and an acid selected from the group consisting of lower fatty acid and benzoic acid.

6. l-ketoprogesterone.

7. An ester of l6-keto-l l-desoxycorticosterone and an acid selected from the group consisting of lower fatty acids and benzoic acid.

8. 16-keto-l l-desoxycorticosterone.

9. 16-keto-l7-hydroxy-l l-desoxycorticosterone acetate.

10. 16-keto-l7-hydroxy-l l-desoxycorticosterone.

11. 16a-hydroxy-A -androstene-3-one-17p carboxylic acid.

12. Methyl 16a-hydroxy-A -androstene-3-one-17,8-carboxylate.

13. Methyl A -androstene-3,l6-dionerl 7fi-carboxylate.

14. A -androstene-3,16-dione.

15. A steroid of the general formula References Cited in the file of this patent UNITED STATES PATENTS Marker Dec. 15, 1942 Chinn et a1. Dec. 20, 1955 

1. A PROCESS OF OXIDIZING A 16-HYDROXY STERIOD WHICH COMPRISES REACTING A 16-HYDROXY STERIOD OF THE GENERAL FORMULA
 15. A STERIOD OF THE GENERAL FORMULA 